Apparatus for the detoxification of exhaust gases of internal combustion engines

ABSTRACT

An after burning device for an internal combustion engine has an inner combustion chamber totally enclosed in an outer, heat insulated combustion chamber. Some of the exhaust gas conduits form the engine exhaust directly into the outer chamber, while other exhaust gas conduits pass through the outer chamber and are exhausted into the inner chamber.

United States Patent Santiago et al.

54] APPARATUS FOR THE DETOXIFICATION F EXHAUST GASES OF INTERNAL COMBUSTION [451 Nov. 21, 1972 [56] References Cited UNITED STATES PATENTS ENGINES 3,413,803 12/1968 Rosenlund ..60/282 [72] Inventors: Andressanfiago; Enrique Santiago, 3,581,494 6/ 1971 Schertlm ..60/282 0f Augsburg Germany Y FOREIGN PATENTS OR APPLICATIONS [731 sigma zeuna'staerk" Augsburg 319,426 9/1929 Great Britain ..60/3l3 many [22] Filed: Sept. 13, 1971 Primary Examiner-Douglas Hart 21] Appl. No.: 179,758 Passe [57] ABSTRACT Forelgn Apphcauon Pnomy Data An after burning device for an internal combustion P 16, 1971 Germany 20 658-0 engine has an inner combustion chamber totally ena closed in an outer, heat insulated combustion [52] U-S. Cl. /313, chamber. some of the exhaust gas conduits form the 181/40 engine exhaust directly into the outer chamber, while [5]] InLCl. ..F0ln 3/10, F02) /10 other exhaust gas conduits pass through the outer Field of Search 8 322; chamber and are exhausted into the inner chamber.

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INVENTORS ANDR ES SANTIAGO ENRIQUE SANTIAGO ATTORNEY ,PATENTEDNHVZI I912 3.703.082

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INVENTORS j "j ANDR ES SANTIAGO 9 I u 12 14 I3 ENRIOUE SANTIAGO ATTORNE Y APPARATUS FOR THE DETOXIFICATION OF EXHAUST GASES OF INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION The present invention relates to an apparatus for the detoxification of the exhaust gases of internal combustion engines, especially vehicular engines having several cylinders. Such devices are known as exhaust manifold thermal reactors wherein the exhaust gases are subjected to an after burning process. If necessary, fresh air may be supplied to the exhaust gases emanating from the engine. Usually these reactors comprise two combustion chambers into which separate exhaust gas pipes are discharged.

The detoxification of exhaust gases is not a necessary requirement as far as the operation of the engine is concerned. Rather, the requirement that exhaust gases should be detoxified was made by private and public organizations or institutions which are concerned with the purification of the air. This requirement has received substantial emphasis in view of the increasing traffic density. In some countries, for example, in the United States of America statutory requirements have already been established providing regulations which define the limits of the exhaust gas components dangerous to human health. For example, in the United States it has been established that beginning with the year 1975 the hydrocarbons content of the exhaust gas must be less than 0.5 grams per mile. Carbon monoxide must not exceed 11 grams per mile and nitrogen oxides must be maintained below 0.9 grams per mile. Even stricter limitations have been established for the year 1980. These stricter limitations amount to about one half of the limitations imposed for the year 1975.

The above considerations have led to numerous suggestions aiming at the detoxification of the exhaust gas of internal combustion engines, especially of vehicular engines.

For example, it is known that harmful exhaust gas components may be oxidized by after burning the exhaust gases as they emanate from the engine. In this connection reference is made to the so-called MAN- AIR-OX after burning system in which fresh air is introduced directly down stream of the outlet valves of the engine.

Another known apparatus comprises an after burner device with two or more combustion chambers arranged adjacent to each other and surrounded by a common space for forming an isolating exhaust gas envelope or jacket. The exhaust gas is introduced into each of the combustion chambers from an adjacent engine cylinder. The connection is kept as short as possible in order to maintain any exhaust gas heat loss as small as possible. Secondary air is supplied to the combustion chambers.

OBJECTS OF THE INVENTION In view of the foregoing, it is the aim of the invention to achieve the following objects singly or in combination:

to provide an efficient after burner device for purifying exhaust gases;

to construct an after burner device in such a manner that it permits the separate guiding or piping of several exhaust gas currents;

to arrange the structural components of an after burner device so that it is especially suitable and efficient with regard to thermal and flow considerations; and

to conduct several exhaust gas currents in such a manner that, when they enter into a common conduit, they do not interfere with each other.

SUMMARY OF THE INVENTION According to the invention there is provided an after burning device of the above mentioned type wherein an inner combustion chamber is enveloped by an outer combustion chamber. The outer chamber is provided with outer thermal insulation. The two combustion chambers are sealed from each other, at least to the extent that mixing of the exhaust gases present in the chambers is substantially prevented. The exhaust gas pipes of the individual engine cylinders are selectively connected to the two combustion chambers and distributed in the sense of a power tuning. In other words, the several exhaust gas currents, as far as they are fed in common into one of the after burning combustion chambers, enter such chamber without interfering with each other.

Due to the substantial sealing of the combustionv chambers with respect to each other when the invention is used in an engine having several cylinders, it is now possible that each combustion chamber may be connected either directly or through more or less long exhaust gas conduits to a plurality of exhaust gas connecting pipes having non-interfering cycles, so that the entire exhaust gas volume is distributed to both combustion chambers. Thus the invention teaches for the first time that power tuning may be advantageously employed in an after burner device.

In known after burners, the exhaust gas currents of different cylinders join each other in accordance with the cycle sequence of the engine, whereby such joining takes place subject to the alternating pressure increase and pressure reduction which occur during each cycle sequence. Thus, the exhaust gas currents pulsate in response to said pressure variations which is disadvantageous with regard to the power output of the engine. Contrary thereto, in accordance with the teachings of this invention, the exhaust gas conduits are distributed to the combustion chambers in the sense of power tuning, so that the different exhaust gas currents meet each other without interference. In other words, the above mentioned pulsation is avoided in accordance with the invention.

Feeding several exhaust gas currents without interference into a common after burner combustion chamber not only avoids power losses. It has the further advantage that the flame produced in the after burner need not be alternately extinguished and ignited due to the pulsating exhaust gas flow. On the contrary, according to the invention, the flame in the after burner is continuously maintained since there is an even exhaust gas flow rather than a pulsating flow. This in turn results in uniform after burning and in an efficient use of the available heat of the exhaust gases which enter into the after burner. Accordingly, the after burner of the invention does not require a spark or glow plug or other external ignition means for the exhaust gases. According to the invention, it is possible to sustain an effective self-ignition by means of a glowing surface in each after burner chamber which surface is heated by the exhaust gases.

Due to the additional feature according to the invention that an inner combustion chamber is enveloped by an outer insulated combustion chamber, it is possible to utilize substantially all of the exhaust gas heat in the after burning process. Accordingly, the arrangement of one of the combustion chambers within the other is not merely a spacial feature but unexpectedly it provides an additional improvement in the efficiency of combustion of the after burner.

BRIEF FIGURE DESCRIPTION In order that the invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawings, wherein:

FIG. 1 is a longitudinal section through an after burner combustion device according to one embodiment of the invention;

FIG. 2 is a top view of the combustion device of FIG. 1 illustrating the pipe fittings for the exhaust gas conduits to the engine which, for Simplicitys sake, is not shown;

FIG. 3 is a cross-sectional view taken along the line III-III of the combustion device of FIG. 2;

FIG. 4 is a schematic illustration of a longitudinal section of a further embodiment of a combustion device according to the invention;

FIG. 5 is a cross-sectional view taken along line V- V in FIG. 4; I

FIG. 6 is a schematic illustration of a longitudinal section through a combustion device according to another embodiment of the invention adapted for use on a four cylinder engine;

FIG. 7 is a schematic illustration of a longitudinal section through a combustion device for a six cylinder engine, and

FIG. 8 is a schematic illustration of a modification of the device of FIG. 7.

DETAILED FIGURE DESCRIPTION The longitudinal sectional view shown in FIG. 1 illustrates the basic structural features of one embodiment of an after burner combustion device 1 according to the invention. For the sake of simplicity, elements which serve merely as supporting means between the individual components of the combustion device, i.e., the connections between these components, habe been omitted. The combustion device 1 comprises an outer combustion chamber 2 made of a tubing 6 having closed ends, and an inner combustion chamber 3 formed by a tubing 7 also having closed ends. Pipe fittings 12 and 13 are provided which discharge into the inner combustion chamber 3 and pipe fittings 11 and 14 are provided which discharge into the outer combustion chamber 2. These pipe fittings are connected to the respective cylinders of the engine (not shown). The pipe fittings 12 and 13 are advantageously connected to the outer tubing 6, for example by welding. The inner ends of the pipe fittings 12 and 13 extend relatively loosely through apertures in the wall of the tubing 7 which forms the inner combustion chamber 3. This type of connection is suitable for all pipe fittings which connect the inner combustion chamber with the space outside of the combustion device. The mentioned connections of the pipe fittings 11 to 14 to the engine may comprise suitable flanges. The pipe fittings 11 to 14 may each be connected either directly to the engine block or they may be connected through exhaust gas conduits leading to the engine and connected thereto by means of individual exhaust gas fittings of the engine. The inner combustion chamber 3 is connected to the exhaust gas conduit outlet, i.e., to the exhaust conduit downstream of the after burner combustion device by means of a pipe fitting 4. As shown in FIG. 2, the outer combustion chamber 2 is connected to the exhaust gas conduit outlet by means of a connecting pipe fitting S.

The cross-sectional view of FIG. 3 illustrates the arrangement of the pipe 7 which substantially forms the inner combustion chamber 3 inside the outer combustion chamber 2 which is defined by the outer tubing 6. The tubings 6 and 7 are supported relative to each other by means of supporting brackets 8. These brackets are advantageously connected to a portion intermediate the ends of the inner tubing 7, so that these ends of the tubing 7. are free of any connecting means and thus may expand in response to temperature without any hindrance. The pipe fitting 12 seen in FIG. 3 is, as is the pipe fitting l3, welded at least to the outer sheet metal casing 60 of the insulated outer tubing 6. The inner ends of these pipe fittings 12 and 13 extend through an aperture A in the wall of the inner combustion chamber tubing 7. The aperture A has a slightly larger diameter than the outer diameter of the respective pipe fittings l2 and 13. This detail is not shown in FIG. 3.

A complete sealing of the combustion chambers with respect to each other, although desirable, is not possible, at least in the area of the aperture A where the pipe fittings connected to the outer combustion chamber 2 pass into the inner chamber 3, because it is generally necessary to provide a space between the wall of the inner combustion chamber 3 and the pipe fittings in order to permit thermal expansion of the combustion chamber. Thus, the pipe fittings 12, 13 may be connected in a sealed manner only to the wall 6 of the outer combustion chamber 2. In order to realize this structural feature, which is known, per se, rather narrow gaps at the aperture A are sufficient to prevent interrnixing of the exhaust gases in the inner combustion chamber 3 with those in the outer combustion chamber 2, and thus the power output of the engine is not impaired. Advantageously with this simple construction, the engine output is improved as a result of the above mentioned power tuning and the combustion efficiency in the after burner is also improved, while simultaneously reducing the harmful exhaust gas components. Moreover, this simple structure of the after burner makes it, surprisingly, very efficient.

The outer tubing 6 is heat insulated. An insulating layer 6c is sandwiched between the two sheet metal casings 6a and 6b. According to an alternate embodiment of the invention, the tubing 6 may comprise an inner sheet metal casing covered by an outer layer of insulating material which is provided with a protective coating The inner casing 612 may be provided with corrugations C" which aid in the temperature expansion.

The embodiment of the invention illustrated in FIGS. 1 to 3 of the combustion device is constructed and arranged with due regard to its use with a four cylinder engine, so that the exhaust gas fittings of the four cylinders of the engine are connected to the combustion device by way of separate pipe fittings 11 to 14' respectively. The pipe fittings 11 and 14 may be connected to the first and fourth cylinders of a four cylinder in-line engine, and the pipe fittings 12 and 13 may be connected to the second and the third cylinders. The opposite arrangement is also possible, namely that the first and the fourth cylinders may be connected to the pipe fittings l2 and 13 and the second and the third cylinders may be connected to the pipe fittings 11 and 14.

In the just mentioned embodiments, the exhaust gases which emanate through each exhaust gas fitting of the engine are fed separately to the combustion chambers, and the collection of the exhaust gases of cylinders which are tuned to each other occurs directly in the space of the after burner combustion chambers2 and 3. On the other hand, the exhaust gases in the exhaust gas conduits which are connected to one of the combustion chambers may be combined upstream of V the combustion chamber, as viewed in the exhaust direction of the exhaust gases. This is illustrated in FIG. 4, for example, in this case the exhaust gases may be fed through a common conduit B into the respective combustion chamber. Stated differently, in this instance the combining of the exhaust gases of cylinders which are tuned to each other'takes place prior to the entrance of the exhaust gases into the combustion chamber. The solution suitable for the individual situation must be selected in accordance with the spacial and structural conditions present in any particular vehicle.

When the after burner combustion device according to the invention is in operation, the hot exhaust gases emanating from the pipe fittings l l to 14 produce spots S1 to S4 inside the combustion device shown in FIG. 1. These spots have an especially high temperature. The oxidation of the exhaust gases passing along these spots is greatly facilitated. The spots S1 to S3 are particularly effective in the high local heating of the exhaust gases in the outer combustion chamber 2. The spot S4 produces a substantial heating of the exhaust gases introduced into the inner combustion chamber 3 prior to their exit from the combustion chamber 3.

The present apparatus assures that the exhaust gases are subject to an especially advantageous flow condition. This is accomplished according to the invention by the arrangement of the inner combustion chamber 3 inside the outer combustion chamber 2, as illustrated in FIGS. 1 to 3, as well as by the special arrangement of the pipe fittings 11 through 14 along a generatrix of the tubings 6 and 7 forming the combustion apparatus. It is surprising that in spite of these advantageous flow conditions, the objective of the invention is not impaired at all, namely to keep the exhaust gases inside the combustion device until the desired degree of oxidation of the exhaust gas components has been achieved. Stated differently, the invention combines good flow conditions with an efficient oxidation, two features which have been thought to be mutually exclusive.

Good flow conditions are also provided by a specially advantageous embodiment of the invention in which each of the combustion chambers is formed substantially in the shape of longitudinally extending tubes closed at their ends, so that the tube 7 forming the inner combustion chamber 3 is arranged inside the tube 6 forming the outer combustion chamber 2. The inner tube preferably extends in substantially the same direction as the outer tube, whereby again with due regard to providing good flow conditions, the inner combustion chamber is connected to the exhaust gas conduit system through a pipe fitting 4 extending through an end wall 4 of the outer combustion chamber and the outer combustion chamber is in turn connected to the exhaust gas conduit system through a pipe fitting 5 attached tothe end wall 4 of the outer combustion chamber. These pipe fittings may be attached to and extend through the same end wall 4 as shown, for example, in FIGS. 1 and 2 or they may be attached to and extend through opposite end walls as shown, for example, in FIG. 7.

In connection with the latter feature according to the invention that the pipe fitting of the inner combustion chamber extends through one end wall and that the connecting pipe fitting of the outer combustion chamber extends from the opposite wall of the combustion chambers and substantially in parallel to each other, provides the further advantage that the forces which are effective on the support between the after burner device and the vehicle are balanced.

Incidentally, the above mentioned arrangement of the pipe fittings along the elevation of the generatrix of the outer combustion chamber, substantially reduces the occurence of interfering counter currents in the area or space of the combustion chamber.

FIGS. 4 and 6 show embodiments of a combustion device for four cylinder in-line engines. In the embodiment of FIG. 4, the tubings 6 and 7 forming the combustion chambers 2 and 3 have a circular cross section as is shown schematically in FIG. 5. The primary difference between the embodiment of FIG. 4 and that shown in FIGS. 1 to 3 is that the pipe fittings l2 and 13 as well as 11 and 14 are joined outside the combustion device proper in the arrangement of FIG. 4. Accordingly, the costs for producing the embodiment according to FIG. 4 may be less than those for producing the embodiment according to FIGS. 1 to 3, since fewer apertures are required according to FIG. 4.

In the embodiment of FIG. 6, which schematically illustrates a longitudinal section through the combustion device, the pipe fittings 11 and 14 assure an especially good heating of the exhaust gases present inside the inner combustion chamber 3 because their inner ends are directed toward the tubing 7 which defines the inner combustion chamber 3. Thus the pipe fittings l1 and 14 which blow into the outer combustion chamber 2 efficiently heat the inner combustion chamber 3. Similarly, the efficiency in heating the inner combustion chamber 3 may be further improved in the embodiment of FIG. 1 by positioning the pipe fitting 11 at a slight angle so that its lower opening points toward the end surface of the tubing 7 for better heating the spot S1.

FIGS. 7 and 8 show two embodiments of a combustion device for a six cylinder in-line engine, wherein each set of three cylinders which are tuned relative to each other are combined for connection either to the inner combustion chamber or to the outer combustion chamber. According to FIG. 7, the pipe fittings 9 to 14 are arranged in such a sequence relative to each other that the three pipe fittings 10, 11, and 14 which discharge into the outer combustion chamber 2 are arranged in a first row, followed by a second row comprising the pipe fittings 12, 13, and 9 which are connected to the inner combustion chamber 3, i.e., which discharge into the inner combustion chamber 3. In the embodiments according to FIGS. 7 and 8, the connecting pipe fittings of the outer combustion chambers 2 and the pipe fittings 4 of the inner combustion chambers 3 extend from end surfaces of the respective combustion chambers which are opposite to the end surface from which the other pipe fitting extends, whereas in the embodiments according to FIGS. 1 to 6, the pipe fitting 4 and the connecting pipe fitting 5 are attached to adjacent end walls of the two combustion chambers. It has been found that the arrangement of the fittings at opposite end walls provides a desirable balance of forces as mentioned above.

Suitable materials for manufacturing the combustion device according to the invention are high-alloyed chromium nickel steels having a scaling resistance at temperatures of up to 1,200" C.

Referring again to FIG. 3, the insulation 60 between the outer casing 6a and the inner casing 6b of the tubing 6 forming the outer combustion chamber 2 comprises advantageously fibers of aluminum oxide or of silicone oxide. Other ceramic fibers which are temperature resistant to about 1250" C are also suitable. As mentioned, the inner casing 612 may be provided with corrugations C. It has been found that this feature is advantageous for compensating of different temperature expansions at the inner and at the outer casing wall of the outer tubing 6.

It will be appreciated by those skilled in the art, that there are many modifications of the invention, having regard to the present disclosure. Therefore, only a few especially typical examples as described above, are necessary for elucidating the gist of the present invention. There are many variations possible with regard to the arrangement of the pipe fittings, as well as with regard to the connecting pipe fittings and flanges, whereby proper attention will be paid to the requirements of the particular engine involved. It is thus considered to be unnecessary to illustrate an embodiment of the present combustion device suitable for an eight cylinder engine. Furthermore, although the combustion device of FIG. 3 is substantially rectangular and the combustion device of FIG. 5 is substantially round, it is within the scope of the invention to provide the device with any desired shape. Depending on the space conditions imposed by any particular engine and/or. vehicle the combustion device according to the invention may have a longitudinal shape, as shown in the examples but it may also have a bent shape whereby the tubings forming the two combustion spaces will simply be bent into the desired configuration or shape, especially in the event that the available space is small.

Advantages of the invention are seen in the efficient after burning of combustion engine exhaust gases without a noticable loss of power which otherwise would be due to the flow structure. The exhaust gases according to the invention flow either through the inner or through the outer combustion chamber, so that all walls of the combustion device are maintained at high temperature due to the arrangement of one combustion chamber within the other. This is of substantial importance for the exothermically proceeding after burning process. Moreover, by arranging separate combustion chambers in a manner taught by the invention, the invention has provided a system which meets the requirements of modern high power engines with regard to the specific engine power. On the other hand, the invention also enables treatment of the exhaust gases in such a manner that the desirable substantially complete after burning of two harmful exhaust gas components, i.e., hydrocarbons and carbon monoxide, is achieved. 7

In view of the foregoing, it will be appreciated that it is intended to cover all modifications and equivalents within the scope of the appended claims.

What I claim is:

1. In an apparatus for the detoxification of the exhaust gases of an internal combustion engine having several cylinders, by after burning the exhaust gases in a plurality of afterburner combustion chambers, into which separate exhaust gas conduits from said engine discharge the exhaust gases, the improvement compris-' ing an outer after burner combustion chamber, an inner after burner combustion chamber, means for supporting the inner combustion chamber inside said outer combustion chamber, heat insulation means surrounding said outer combustion chamber, means for sealing said combustion chambers with respect to each other to substantially prevent intermixing of the exhaust gases present in the combustion chambers and separate conduit means for connecting said chambers to said engine, said conduit means being allocated to the individual engine cylinders so that the cylinders are distributed to the two combustion chambers in the sense of power tuning, whereby the exhaust gas currents flowing into the same after burner combustion chamber enter said chamber without interfering with each other.

2. The apparatus according to claim 1, further comprising collection conduit means upstream of each of said after burner combustion chambers, and means for discharging the exhaust gases of said engine through said collection conduit means into the respective one of said combustion chambers. I

3.T he apparatus according to claim 1, for use in a four cylinder four stroke in-line engine, comprising means for supplying the exhaust gases of the first and of the fourth cylinder of said engine to one of the combustion chambers and means for supplying the exhaust gases of the second and third cylinders of said engine to the other of the combustion chambers, whereby the exhaust gas currents fed into the same chamber are in phase with each other.

4. The apparatus according to claim 1, for use in combination with a six cylinder four stroke in-line engine comprising means for supplying the exhaust gases of three cylinders to one of the after burner combustion chambers and means for supplying the exhaust gases of the remaining three cylinders to the other after burner combustion chamber, whereby the exhaust gases of each group of three cylinders are combined in the sense of power tuning.

5. The apparatus according to claim 1, wherein the inner and outer combustion chambers comprise respective tubes of substantially longitudinal shape, means for closing the ends of said tubes, means for mounting said tube forming the inner combustion chamber inside said tube forming the outer combustion chamber, both of said tubes extending in substantially the same direction, said apparatus further comprising a conduit system for the exhaust gases, pipe fitting means extending through said closing means of the outer combustion chamber and into said inner combustion chamber for connecting said conduit system for the exhaust gases to said first chamber, and a connecting pipe fitting flanged to said closingmeans of said outer combustion chamber for connecting said conduit system to said outer combustion chamber.

6. The apparatus according to claim 5, wherein said tubes forming said combustion chambers have substantially round cross sections.

7. The apparatus according to claim 5, wherein said tubes forming said combustion chambers have oval cross sections.

8. The apparatus according to claim 5, wherein said pipe fitting means extending into said inner combustion chamber and the connecting pipe fitting means flanged to said outer combustion chamber extend from adjacent end walls of the combustion chambers and substantially parallel to each other.

9. The apparatus according to claim 5, wherein said pipe fitting means extending into said inner combustion chamber and the connecting pipe fitting means flanged to said outer combustion chamber extend from opposite end walls of the combustion chambers and substantially in parallel to each other.

10. The apparatus according to claim 1, wherein said inner combustion chamber extends over a portion of the length of said outer combustion chamber, and wherein said exhaust gas conduit means which discharge into said outer combustion chamber is positioned to discharge into that portion of said outer chamber which is free of said inner chamber.

11. The apparatus according to claim 10, wherein said exhaust gas conduit means comprises first and second pipe fittings for connecting the engine to said inner and outer combustion chambers, said apparatus further comprising exhaust pipe means connected to said inner chamber and extending outwardly through said outer chamber, at least one of said pipe fittings being positioned so that its discharge end points toward said exhaust pipe of said inner combustion chamber.

12. The apparatus according to claim 1, wherein said outer combustion chamber comprises a tube having closed ends, said exhaust gas conduit means comprising a first plurality of pipe fittings which exhaust into said inner combustion chamber and a second plurality of pipe fittings which exhaust into the outer combustion chamber, wherein all of said second plurality of pipe fittings are positioned at the level of a common generatrix of said tube, and wherein all of said first plurality of pipe fittings extends through said tube along said common generatrix.

13. The apparatus according to claim 1, wherein said inner and outer combustion chamgers com rise inner and outer tubes respectively, sai appara us further comprising supporting brackets connected to the inner wall of said outer tube for supporting said inner tube inside the outer tube, said supporting brackets being attached to said inner tube intermediate the ends of said inner tube, whereby the free ends of said inner tube facilitate the heat expansion.

14. The apparatus according to claim 1, wherein said outer combustion chamber comprises two sheet metal casings and an insulating layer sandwiched therebetween, the inner of said sheet metal casings having corrugations extending thereabout perpendicularly to the longitudinal extension of said outer chamber for compensating heat tensions, especially different heat tensions in the inner and outer casing.

15. The apparatus according to claim 1, further comprising at least one glowing surface in each of said combustion chambers.

16. The apparatus according to claim 15, wherein the same glowing surface is arranged to be effective in the inner combustion chamber and in the outer combustion chamber.

17. The apparatus according to claim 15, wherein said conduit means have discharge end means inside said outer combustion chamber located in such position that the exhaust gases impinge upon said inner combustion chamber for heating a wall portion of said inner combustion chamber to provide said glowing surface.

18. The apparatus according to claim 1, wherein said inner and outer combustion chambers are made of high alloyed chromium nickel steel.

, UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3.703.082 Dated November 21 1972' In ANDRES SANTIAGO ET AL It is certified that error appears in the above-identified patent and that said Letters Patentare hereby corrected as shown below:

On the cover sheet [30] the priority date "Sept. 16, 1971" should read Sept. 16, 1970 Signed and sealed this 15th day of May 1973.

(SEAL) Attest: v I 4 EDWARD M.FLETCHER,JR 7 ROBERT GOTTSCHALK v Attesting Officer Commissioner ofPatents 'ORM Po-1os0 (10-69) uscoMM-oc scan-ps9 fi U.5. GOVERNMENT PRINTING OFFICE; 1969 0-356-334, 

1. In an apparatus for the detoxification of the exhaust gases of an internal combustion engine having several cylinders, by after burning the exhaust gases in a plurality of after burner combustion chambers, into which separate exhaust gas conduits from said engine discharge the exhaust gases, the improvement comprising an outer after burner combustion chamber, an inner after burner combustion chamber, means for supporting the inner combustion chamber inside said outer combustion chamber, heat insulation means surrounding said outer combustion chamber, means for sealing said combustion chambers with respect to each other to substantially prevent intermixing of the exhaust gases present in the combustion chambers and separate conduit means for connecting said chambers to said engine, said conduit means being allocated to the individual engine cylinders so that the cylinders are distributed to the two combustion chambers in the sense of power tuning, whereby the exhaust gas currents flowing into the same after burner combustion chamber enter said chamber without interfering with each other.
 1. In an apparatus for the detoxification of the exhaust gases of an internal combustion engine having several cylinders, by after burning the exhaust gases in a plurality of after burner combustion chambers, into which separate exhaust gas conduits from said engine discharge the exhaust gases, the improvement comprising an outer after burner combustion chamber, an inner after burner combustion chamber, means for supporting the inner combustion chamber inside said outer combustion chamber, heat insulation means surrounding said outer combustion chamber, means for sealing said combustion chambers with respect to each other to substantially prevent intermixing of the exhaust gases present in the combustion chambers and separate conduit means for connecting said chambers to said engine, said conduit means being allocated to the individual engine cylinders so that the cylinders are distributed to the two combustion chambers in the sense of power tuning, whereby the exhaust gas currents flowing into the same after burner combustion chamber enter said chamber without interfering with each other.
 2. The apparatus according to claim 1, further comprising collection conduit means upstream of each of said after burner combustion chambers, and means for discharging the exhaust gases of said engine through said collection conduit means into the respective one of said combustion chambers.
 3. The apparatus according to claim 1, for use in a four cylinder four stroke in-line engine, comprising means for supplying the exhaust gases of the first and of the fourth cylinder of said engine to one of the combustion chambers and means for supplying the exhaust gases of the second and third cylinders of said engine to the other of the combustion chambers, whereby the exhaust gas currents fed into the same chamber are in phase with each other.
 4. The apparatus according to claim 1, for use in combination with a six cylinder four stroke in-line engine comprising means for supplying the exhaust gases of three cylinders to one of the after burner combustion chambers and means for supplying the exhaust gases of the remaining three cylinders to the other after burner combustion chamber, whereby the exhaust gases of each group of three cylinders are combined in the sense of power tuning.
 5. The apparatus according to claim 1, wherein the inner and outer combustion chambers comprise respective tubes of substantially longitudinal shape, means for closing the ends of said tubes, means for mounting said tube forming the inner combustion chamber inside said tube forming the outer combustion chamber, both of said tubes extending in substantially the same direction, said apparatus further comprising a conduit system for the exhaust gases, pipe fitting means extending through said closing means of the outer combustion chamber and into said inner combustion chamber for connecting said conduit system for the exhaust gases to said first chamber, and a connecting pipe fitting flanged to said closing means of said outer combustion chamber for connecting said conduit system to said outer combustion chamber.
 6. The apparatus acCording to claim 5, wherein said tubes forming said combustion chambers have substantially round cross sections.
 7. The apparatus according to claim 5, wherein said tubes forming said combustion chambers have oval cross sections.
 8. The apparatus according to claim 5, wherein said pipe fitting means extending into said inner combustion chamber and the connecting pipe fitting means flanged to said outer combustion chamber extend from adjacent end walls of the combustion chambers and substantially parallel to each other.
 9. The apparatus according to claim 5, wherein said pipe fitting means extending into said inner combustion chamber and the connecting pipe fitting means flanged to said outer combustion chamber extend from opposite end walls of the combustion chambers and substantially in parallel to each other.
 10. The apparatus according to claim 1, wherein said inner combustion chamber extends over a portion of the length of said outer combustion chamber, and wherein said exhaust gas conduit means which discharge into said outer combustion chamber is positioned to discharge into that portion of said outer chamber which is free of said inner chamber.
 11. The apparatus according to claim 10, wherein said exhaust gas conduit means comprises first and second pipe fittings for connecting the engine to said inner and outer combustion chambers, said apparatus further comprising exhaust pipe means connected to said inner chamber and extending outwardly through said outer chamber, at least one of said pipe fittings being positioned so that its discharge end points toward said exhaust pipe of said inner combustion chamber.
 12. The apparatus according to claim 1, wherein said outer combustion chamber comprises a tube having closed ends, said exhaust gas conduit means comprising a first plurality of pipe fittings which exhaust into said inner combustion chamber and a second plurality of pipe fittings which exhaust into the outer combustion chamber, wherein all of said second plurality of pipe fittings are positioned at the level of a common generatrix of said tube, and wherein all of said first plurality of pipe fittings extends through said tube along said common generatrix.
 13. The apparatus according to claim 1, wherein said inner and outer combustion chambers comprise inner and outer tubes respectively, said apparatus further comprising supporting brackets connected to the inner wall of said outer tube for supporting said inner tube inside the outer tube, said supporting brackets being attached to said inner tube intermediate the ends of said inner tube, whereby the free ends of said inner tube facilitate the heat expansion.
 14. The apparatus according to claim 1, wherein said outer combustion chamber comprises two sheet metal casings and an insulating layer sandwiched therebetween, the inner of said sheet metal casings having corrugations extending thereabout perpendicularly to the longitudinal extension of said outer chamber for compensating heat tensions, especially different heat tensions in the inner and outer casing.
 15. The apparatus according to claim 1, further comprising at least one glowing surface in each of said combustion chambers.
 16. The apparatus according to claim 15, wherein the same glowing surface is arranged to be effective in the inner combustion chamber and in the outer combustion chamber.
 17. The apparatus according to claim 15, wherein said conduit means have discharge end means inside said outer combustion chamber located in such position that the exhaust gases impinge upon said inner combustion chamber for heating a wall portion of said inner combustion chamber to provide said glowing surface. 